Communication between vlans will be affected.-although a switch is used to create vlans, a router is required to forward traffic from one vlan to the other as each vlan is a subnet. a router connects two subnets together and is responsible for forwarding traffic between the subnets. thus, if the router fails communication between the vlans will be affected.references:david groth and toby skandier, network+ study guide (4th edition), sybex, alameda ca, 2005, pp. 10-11, 12, 52.david groth, network+ study guide (2nd edition), sybex, alameda ca, 2001, pp. 11-12, 23.david groth and dan newland, a+ complete study guide (2nd edition), sybex, alameda ca, 2001, pp. 313-314.